The present specification generally relates to a near-field super-resolution optical cover glass slip or mount, and more specifically to a near-field super-resolution optical cover glass slip or mount capable of resolving the optical information on the sample surface without optical diffraction limit.
The conventional optical cover glass slip or mount is used to fix and carry the sample in coordination with the conventional optical microscope to carry out optical microscopic observation. The conventional optical microscopic observation is conducted using far-field optical observation (i.e. the distance between sample and sensor is much larger than the optical wavelength used for microscopic observation). It is unavoidable that an optical interference or diffraction phenomena will occur due to the wave characteristics of optics, and the spatial resolution of the conventional optical microscope is limited by the optical diffraction limit (1.22 xcex/2n sin xcex8, where xcex is the wavelength of the light used for the observation, n is the refractive index of the medium, and xcex8 is the half angle of the aperture). To increase the spatial resolution of the conventional optical microscopy, it is required to use the light source with much shorter wavelength such as blue light, or to use an objective lens with high numerical aperture value or to operate the microscopic observation in high refractive index medium condition.
An approach to breaking through the optical diffraction limit, as indicated in U.S. Pat. No. 4,917,462, is near-field scanning optical microscopy (NSOM). By using an optical fiber probe with an aperture of several tenths of nanometers NSOM can perform precise near-field optical observation on the surface of a sample, and the information of near-field optical interactions can be acquired. Because the optical information is obtained from the near field, there is no optical diffraction limit. The spatial resolution of NSOM depends on the local region of the near-field optical interactions between the sample and fiber probe, and are thus mainly related to the size of the optical aperture of the fiber probe and the precision of the scanning control of NSOM system.
The other patents, U.S. Pat. Nos. 4,917,462, 5,894,122, 5,994,691, 6,194,711 also proposed a near-field scanning optical microscope (NSOM) technique which can break through the optical diffraction limit; however, the NSOM scanning system needs a very precise feed back control, and ultimately will slow down the scanning speed, and will also restrict the scanning area to a limited region. The optical fiber probe of NSOM is fragile and easily damaged during microscopic observation as well.
In applications of the near-field optical storage, in order to overcome the drawbacks mentioned above, and to develop a commercial near-field optical recording product, U.S. Pat. Nos. 6,226,258, 6,319,582, 6,340,813 by Dr. Junji. Tominaga disclosed that additional double layers of nanometer-scale thin films in the structure of the normally used phase-changed optical disk could perform the near-field optical recording. These two layers of thin films are 20 nm of SiN and 15 nm of Sb, respectively, which are used to replace the function of the optical fiber probe of the NSOM, and to carry out the read/write actions beyond the optical diffraction limit.
The present invention applies a similar aforementioned ultrahigh density near-field optical recording method to the field of super-resolution optical microscopic technique. A layer of nano structure which is capable of producing localized nonlinear near-field optical interactions, and a second layer of optical transparent dielectric thin film which is capable of protecting the previous nano thin film, and maintaining the optical interactions of the previous nano thin film within the near field to obtain the super-resolution beyond the optical diffraction limit.
The near-field super-resolution optical cover glass slip of the this invention is designed to coat a nanometer structured thin film on the glass, and the focused light will excite the localized near field of this nano structured thin film which is then coupled to the nano-structure of the observed entity to obtain the optical information of the sample surface within the near field distance. The near-field super-resolution optical cover glass slip can easily fix and carry the sample as the conventional optical cover glass slip does. The usage of the near-field super-resolution optical cover glass slip can directly increase the spatial resolution of the conventional scanning optical microscopy beyond the optical diffraction limit, and preserve all the advantages of the conventional scanning optical microscope.